One problem in the X-Ray spectroscopic industry is precision positioning the sample to be analyzed in the sample holder so that the sample is repetitively and precisely aligned with the "hot spot", or point of primary focus, of the X-Ray spectrometer beam to assure reliable replicate analytical readings from sample to sample. Constant realigning of each batch of samples is necessary since the hot spot tends to drift slowly and irregularly around the area of the striking beam.
One method of sample alignment used in the spectroscopic industry at present is as follows. The analyst empirically determines the position of the hot spot by empirically reading the X-Ray energy output across the analytical sample area and marks the results of the empirical readings onto a grid. A number of data readings results in the ability to pinpoint X-Y readings onto the grid and leads to a final measurement of the hot spot. The sample holder with the sample is then placed on a grid and the sample is aligned with the data reading of the hot spot. The problem with this reading is that the sample holder can move slightly during the aligning process with the result that the possibility of human error is greatly increased with repeated positionings of analogous samples with the result that the scientific basis of the analysis can be questioned.
Another method of sample holder alignment used in the industry today is similar to the method just described, except that a 35 mm slide holder with a transparent film window is used. The slide holder is generally square and fits into a square recess under the beam of the X-Ray spectrometer. Slide-type sample holders, however, are not adapted to grip a film layers of film between which the sample is located in a firm and taut manner, with the result that the film layers tend to crease, or wrinkle, in a large percentage of cases. If a wrinkle shifts even slightly, the sample will be misaligned relative to the hot spot and the results of the reading will be faulty.
The scientific worth of an X-Ray spectroscopic analysis is based upon the capacity to obtain and duplicate results from sample to sample. For that, several factors have to be controlled. One of these factors is the ability to place the sample in the hot spot each time an analysis is made.
Yet another problem of the spectroscopic industry is that of interference with the primary X-Ray beam by rays reflected from the inner surface of the sample holder. This type of interference occurs because of the comparatively high walls of the sample holder, which reflect the rays that bypass the sample from below, pass to the sides of the walls, bounce around the inside of the holder and generally create a static or noise that can actually be reflected to the analyzer of the spectroscope so as to add background signals that tend to obscure the desired wavelengths.
What the industry needs is a system of obtaining reproducible values from the spectroscopic analysis of a sample by precisely positioning the sample in an optimum repetitive, or sample-to-sample, location along with a system that provides a stable environment for the mini-/micro-sample positioned between two layers of thin film that are flat and taut.